Is the Monsoon Coming? There Are Signs

The typical arrival of the monsoon season in the Southwest deserts is the first week of July, on average. The monsoon officially begins as defined by three consecutive days with dew points of 54 degrees or higher. While there has been an unusual amount of convection in parts of the Great Basin to the Southwest in the last few weeks, this has not been from any monsoon but by unseasonably cool upper-level troughs bringing middle- and high-level moisture out of the subtropics.

For a couple of days now, most very long range models have shown the typical 4-corners upper-level high developing toward the very end of June and the start of July. If this indeed happens, then this will bring the opportunity for those dew points to rise to the necessary levels finally.

This is what the GFS 500 mb pattern is forecast to look like on June 30.

Here are some statistics about normal rainfall for the monsoon season (June 15 through September), the wettest and driest seasons and what occurred last year.